Process of making filaments.



- the filamentous paste,

\ No Drawing.

RALPH E. Mu 3&0]? EAST ORANGE, JERSEY, ASSIGNOR TO WESTINGHOUSE LAMP COMPANY, A CORPORATION IE'JENNSYJE-V'AINIAa menace,

To all whom it may concern:

Be it known that I, BALI-n E. MYERS, a citizen of the United States,and a resident of East Orange, in the county of Essex and State of New Jersey, have invented a new they are previous to the application ofthe treatment.

The process consists in first producing the material of which the filament is composed in filament or wire form' according to any known or. desired process, as by mixing a finely divided metal, such as molybdenum, tungsten, tantalum, or other refractory metal with a binder, squirting this paste through a die, and then treating it to carbonize and remove the binder and to sinter the ,finely divided particles together, the final step on steps .of the treatment preferably being accomplished by passing an electric current through the material. A further treatment 'is then applied to the material which consists of again heating .it

for a short period, as by passing current through it, but to a lower temperature than that employed for sintering purposes, this further treatment being applied in the air and apparently serving to anneal the material, as itis thereby rendered much more ductile and tenacious than it is previous to the application thereto of'such treatment. ll ire produced according to this process may be handled and manipulated at pleasure without breakage, and because of its high fusing point, it is particularly suitable for use in making anchors or supports for tungsten and other metallic filaments, especially when composed of molybdenum.

In practising the present process, I prefer to carry it on continuously, as by passing as it leaves the die,

- through, or in engagement with, a series 0 electrical terminal" devices by 1 means of which gradually-increasing amounts of our- Specification of Letters Patent.

Patented a t-via, rain I Application filed December 5, 1910., Serial No. 595,672.

rent may be applied to the moving material in order to giveit the ordinary treatment, and whereby an annealing current or temperature may also be applied to the material after it has been sintered. The cooling of the material is preferably 'eifected gradually. After the filament has been thus treated, it may sometimes be desirable to reduce its diameter, as by drawing it through a die or swaging it by impact, or by any known or desired means, and then to re-anneal it by heatingin the air and cooling,'t he reducing in diameter, heating and cooling treatments being successively applied until the filament has been reduced to the'desired diameter and rendered suiticiently ductile and tenacious. reduction in the diameter of the filament it will usually be found advantageousto first heat it to-a higher temperature than that used for the first annealing and then to reduce its'temperature to approximately that used for the first annealing. 1

Prior attempts to anneal bodies of tungsten, molybdenum and similar metals have always included the step of inclosing the metal to be annealed in a vacuum or in a. non-oxidizing atmosphere? 1 have discovered that the annealing process may be carried out in the air and without special precautions against oxidation, except that the heating, as indicated above, must continue for a shorttime only., My process, as set;

forth above, is therefore superior to previously known processes in simplicity as well as efficiency. Furthermore, l have discovered the rather surprising fact that, when refractory metals are annealed in the pres ence of air or other oxidizing medium, the resulting products are less brittle and more uniform in structure. than the products produced by annealing in a. vacuum or in an inert atmosphere. For example, molybdenum'wire when annealed in an atmosphere of hydrogen is brittle in spots, while the same variety of wire, annealed in the same manner but in the presence of air, is entirely uniform and thoroughly annealed. The reasons for this improvement are somewhat obscure. by oxidation, and such decarbonizing may account for the improved quality of the product. llhis, however, is not certain, and I do not wish to be limited by any definite After each It may be that carbon is removed 7 theory of chemical or physicalaction. It

; is a fact, however, that the beneficial results The foregoing. treatment produces a coating of oXid upon the surface of the metal,

which may be removed, if desired, by heat-. ing in hydrogen after-the annealing step,

I claim as my invention: I

1 The process of manufacturing fine ductile filaments from wire of refractory conducting material which consists in drawing the wire through a die; and subsequently heating'the product in the presence of oxyen. v g 2. The process of manufacturingfine ductile filaments from .wire' of refractory conducting material which consists in drawing the wire through a die, heating the product to an annealing temperature in the presence of air and allowing the same to cool.

3. The process of manufacturing fine ductile filaments from wire of refractory conducting material which consists in successively drawing the Wire and-heating it in an oxidizing atmosphere until a product of the desired diameter is obtained.

4. The combination with the. step of intility of the wire by heating in the presence of air.

'Tliexcombination with the step of increasing the ductility of a wire of refractory material by drawing through a die, of the step of increasingthe ductility of the product by heating in the presence of air. 6. The combination with the step of increasing the ductility of a body of refractory conducting material by successive mechanical workings, of the step of increasing the ductility of the product by successive heating in the presence of air, the two steps being applied alternately.

7.- The process of manufacturing formed articles of refractory electrically-conducting material which consists in successively subjecting the said material to mechanical working and to heat applied in an oxidizing atmosphere.

8. The process of manufacturing formed articles of refractory electrically-conducting material which comprises mechanically working thesaid material and heating the product in an oxidizing atmosphere.

In testimony whereof, I have hereunto subscribed my name this 23rd day of November, 1910.

RALPH E. MYERS. 

